This study focuses on the retinal catabolism of photoreceptor outer segments by lysosomes in the retinal pigment epithelium of the eye. We are investigating lyosomal function, autophagic mechanisms and pigment metabolism (mainly lipofuscin) in the normal retina of the rat, dog and bovus. Chief attention is being paid to the neuroretina and the retinal pigment epithelium where the biochemical events associated with the formation of the autophagic vacuole, and the transformation of these vacuoles to residual bodies are being studied. We are continuing studies on one form of hereditary retinal degeneration in the dog. The investigations are directed toward the cellular and subcellular biochemical events associated with a canine ceroid storage disease in the eye. Briefly, the results to date show that the initial events in this disorder include a decrease in peroxidase and a gradual inability of the eye to cope with peroxidative damage followed by an exaggerated attempt by the retinal pigment epithelial cell to digest the accumulating masses of autofluorescent lipopigment.